Although mounting 100mm guns on heavy tanks was very appealing, several things including lack of necessary ammunition, hampered their mass implementation. Firsts attempts to use a 100mm gun with ballistics of a Naval AA Gun B-34 for arming heavy tanks were made by TsAKB, designing two models during autumn of 1943. One of them was 107mm ZIS-6 Gun re-bored for 100mm calibre with a modified brass catcher and vertical aiming device, and the second one 100mm Tank Gun S-34. Judging by the NKV letter exchange, we can suppose that in September one of the models was field tested from the mount of a 152mm Howitzer ML-20. Results however are unknown, and so is the index of the weapon.

On December 27th, 1943 a decision came from GKO No.4851 about the conversion of the tank JS and self-propelled artillery with a 100mm gun, modified with an easier to use loading mechanism. Obeying the decision, Test Factory No.100 manufactured two JS tanks converted to a 100mm gun. Essentially, based on the GKO decision only the tank JS-100 was supposed to be armed with an S-34 Main Gun, but the mounting required modification of the internal module, which the tank factories didn't like. Because of that, in April of 1944 OKB No.9 suggested its variant of the 100mm Gun D-10, whose mounting did not require any modification to the turret of the tank.

Tank with a 100mm Gun D-10T received the designation JS-4 (Object 245). First testing of the tank was unsuccessful like the JS-5, armed with an S-34 Gun. The same defects were noted, such as a weak gun cradle, badly sealed recoil brake and some more. The gun was returned for repairing, but the field officers more liked the tank fitted with an S-34, that alleviated the task of the gunners.

From July 1st to 6th 1944, on the Gorokhovetskiy proving grounds, tandem field testing of the D-10 OKB No.9 and S-34 TsAKB guns mounted in tanks JS-4 and JS-5 continued. Now the reliability of the D-10 was noted, but the impressions were spoiled by the insufficient ammunition storage (30 shells), bad ventilation of the gunner module and strain on the loading gunner.

Parallel to these tests, OKB No.9 and the 520th Department of Factory No.183 received and assignment to mount a 100mm gun in the turret of a T-34. This decision was made due to the insufficient HE power of 85mm guns in battles against long-term fortifications. However, even the drafting of the project showed that the mounting and use of a 100mm gun on a T-34 would be hampered by the 1600mm diameter of the turret ring. Use of a JS turret with a turret ring diameter of 1850mm wasn't possible due to the need of manufacturing an absolutely new body, especially complicated by the T-34's «candle» suspension. Nonetheless, OKB No.9 experimented with mounting a 100mm D-10 Gun in a standard turret, but the details of this project are unknown.

It should be noted that an armor-piercing shell for a 100mm gun was in production only in November of 1944, when it was found out that due to the significant degradation of armor on German tanks, the effectiveness of the 122mm guns mounted on the JS tanks significantly increased. Besides that, test shelling of the German Panthers on Kubinka GABTU extreme effectiveness of 122mm shells against Panther's front armor. With the explosive shells, 122mm shell was superior to that of the 100mm, which is why GKO made a decision against the mount of D-10 in heavy tanks, which is indicated in mail about the mounting of 100mm gun on the JS tanks. proving grounds in September 1944 proved the

Another attempt at up-gunning a T-34 to a 100mm gun was tied with the design of the tank T-44V. By the initiative of A. Morozov, permitted by the Narkomtankprom (Minister of Tank Industry), for construction design of the T-44V turret, the 520th Department lead by Doroshenko designed a «mobile stand» from the body and devices of the T-34, where the new turret was mounted. This project received a factory index T-34-100. In February-March of 1945, this tank was field tested with guns ZIS-100 and D-10 on the Sverdlovsk and Gorokhovo proving grounds. The testing was generally successful, but the accuracy of the shells wasn't good, and the recoil reaction on the suspension too great. Nonetheless the military personnel liked the vehicle that demanded continuation of work on it, with a possible goal of strengthening the armament of the T-34-85. However, all attempts to increase accuracy of the D-10 and minimize the recoil reaction failed. The T-34–100 project was abandoned, especially since at that moment the T-54 tests were conducted.

During 1945–47, the D-10 was mounted in experimental tanks T-44-100, whose 85mm armament was deemed insufficient, as well as various modifications of experimental T-54. As a result, the superiority of the D-10 above others was confirmed, since the gun didn't have a muzzle brake and was more compatible than others for arming a medium tank.

During the whole war the only BR-412 APHE projectile used, in 1946-1950th some improved projectiles were developed, for example BR-412D and BR-412B.

*Certified Penetration (CP) means the 80% probability of armor penetration;
Muzzle velocity for the AP projectile — 880 m/s.

*Note: this table does not reflect some post-war projectiles.

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Sources: A. Shirokorad «Entsiklopediya Otechestvennoi Artillerii», 2000
Entsiklopedia Vooruzhenii KiM
«Artillerijskoye Vooruzhevie Sovetskikh Tankov 1940-1945» Armada-Vertical, No.4, 1999